Serve practice mode from the main server, add mode switch, fix touch

Practice mode is now at /practice on server.py instead of a separate
server, with a button in the bottom-right corner of each page to the
other mode. Touch: no double-tap zoom, no sticky hover after a tap, no
long-press selection on the board, and a pressed look on tapped squares.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

tests/test_practice.py

@@ -1,23 +1,28 @@
 from aiohttp.test_utils import AioHTTPTestCase
 
-import practice
+import server
 
 EMPTY = {"history": [[], []], "turn": 0}
 
 
 class PracticeTest(AioHTTPTestCase):
     async def get_application(self):
-        return practice.make_app()
+        server.rooms.clear()
+        return server.make_app()
 
     async def play(self, body):
         res = await self.client.post("/api/play", json=body)
         return res.status, await res.json()
 
     async def test_page_served(self):
-        res = await self.client.get("/")
+        res = await self.client.get("/practice")
         self.assertEqual(res.status, 200)
         self.assertIn("practice.js", await res.text())
 
+    async def test_pages_link_to_each_other(self):
+        self.assertIn('href="/practice"', await (await self.client.get("/")).text())
+        self.assertIn('href="/"', await (await self.client.get("/practice")).text())
+
     async def test_human_move(self):
         status, s = await self.play({**EMPTY, "cell": 4})
         self.assertEqual(status, 200)